Once you start to decode EME signals, it
is natural to want to have a go, but before you do this, make sure that you
understand the procedure used in an EME QSO.
This has evolved over many years so as to optimize the chance of completing the
QSO, and it is surprising how many stations fail to follow it closely.
Joe Taylor has written a concise Help entry in the WSJT program - click on Help,
then What Message to Send? Study this carefully and make sure that you
understand it fully - this will take longer than you think!
Stick to the basic procedure exactly until the QSO is legally complete, only then add some chit-chat if you want.
The formal requirements for completion of a QSO are:
It is not permitted to send the O
report until you have copied both callsigns.
This may seem to be an unnecessary restriction, but it avoids ambiguity under
marginal conditions.
If you receive an OOO report, you can be sure that the other station has
copied both callsigns, and you need not send callsigns any longer.
In a typical sched situation, both
stations start by sending callsigns.
The grid locator is attached by the program, and is useful for locating stations
when collecting gridsquares, but the grid is not formally required for the QSO
to be complete.
When either station decodes both
callsigns, he responds by attaching his report OOO to the callsigns he
continues to send.
If you receive callsigns + OOO, then you know that both stations have
now copied both callsigns, and that you have received a report.
So you respond by acknowledging the other station's report with R, and also
sending your report O to him, put together as RO.
Once he receives your RO, the only thing missing is his acknowledgement that
he has received your O (part of the RO).
He therefore responds with RRR, and as soon as you receive that, the QSO is
legally complete.
It all sounds more complicated than it really is, but you do need to grasp it thoroughly.
Notice that when you receive his RRR,
you know that the QSO is complete, but the other station does not
know this until you tell him so by sending 73.
A lot of twaddle has been written by experienced operators to the effect that if
both stations don't know that the QSO is complete then it isn't. This is
obviously rubbish!
The QSO is complete at the time that one station (suppose it to be you) receives
RRR.
Now suppose that before you can send him 73 to tell him of the completion,
your transmitter blows up (this really happened to me once), the mains power
supply fails, your computer crashes, or the moon sets.
There is no way he can know that the QSO is complete until you tell him (by
email, logger, post, or whatever). But the QSO was still legally complete.
There is no way
out of this bind. Suppose the rules were changed to require your 73 to be
received by the other station before the QSO could be deemed complete.
Now suppose his transmitter blows up after receiving your 73, but before he
can tell you this .....
Look at the
list of messages provided in JT65B. Messages 2 to 4 are each sent by only ONE of
the two stations, and follow in a natural sequence.
Message 1 may well be sent by both stations in a sched situation (but not
necessarily), and it is polite for both stations to send 73, but you should
never respond to RO with RO, or RRR with RRR.
It simply isn't necessary, and the wasted time may make the QSO impossible to
complete.
That said, if you understand the requirements then you can easily improvise if
the other station gets it wrong.
For example, if
you send him RO and he responds with RO instead of RRR, then
O and R
have been decoded in both directions, and that is all that is required, so the QSO is complete.
You can properly respond with 73, rather than send RRR.
Two small final
things. Some computers are unable to complete the decode before the minute rolls
over and you start transmitting.
No matter, you can change the message in mid transmission without damaging
anything. There is no need to wait for another sequence.
And do make use
of the waterfall display for decoding RO, RRR, and 73. This way you can be ready
for the next step long before the computer does the decode.
Sometimes the computer will even fail to decode one of these shorthand messages
if an interfering signal is close by.
It is often better to turn off the shorthand decodes completely, to avoid a
message being mistakenly decoded as RO, RRR or 73 due to
another sync tone just at the shorthand spacing.
I once had the following JT65B EME
exchange on 144MHz.
I have changed the callsign of the other station to avoid offence.
Each line is tagged at the start with the callsign of the transmitting station.
VK2KU : CQ VK2KU QF55
EU1AA : VK2KU EU1AA JN99 OOO
VK2KU : EU1AA VK2KU QF55 OOO
EU1AA : RO
VK2KU : RRR
EU1AA : RRR
VK2KU : 73
EU1AA: 73
EU1AA made an error in line 2 by sending OOO before he had received both
callsigns - I had not even transmitted his callsign yet!
I therefore ignored the OOO, but since I had received both callsigns, I
responded with callsigns + OOO.
His response of RO and my following response of RRR were correct. When he copied
my RRR, the QSO was legally complete.
EU1AA made a second error by sending RRR when he could have gone straight to 73,
but the QSO then proceeded to a normal completion.
The correct (and expected) sequence of messages for that QSO would have been:
VK2KU : CQ VK2KU QF55
EU1AA : VK2KU EU1AA JN99
VK2KU : EU1AA VK2KU QF55 OOO
EU1AA : RO
VK2KU : RRR
EU1AA: 73
VK2KU : 73